6.3.2 Populations and Sustainability

Question 1

Limiting factor

Answer 1

environmental resource or constraint that limits population growth

Question 2

example of limiting factor

Answer 2

food availability
water availability
habitat availability
competition between organisms for resources
build up of toxic by products of metabolism
disease
predators

Question 3

Phase 1 of population growth graph

Answer 3

slow growth
small numbers initially present reproduce increasing the total population
birth rate is higher than death rate

Question 4

Phase 2 of population growth graph

Answer 4

rapid growth
number of breeding individuals increases
total population multiplies exponentially
no limiting factors

Question 5

Phase 3 of population growth graph

Answer 5

stable state
further population growth is prevented by external factors
population size fluctuates due to limiting factors such as predators but overall size remains stable
birth rate = death rate

Question 6

carrying capacity

Answer 6

maximum population size that an environment can support

Question 7

Immigration

Answer 7

movement of individuals into a particular area increasing population size

Question 8

emigration

Answer 8

movement of individual organisms away from a particular area decreasing the population size

Question 9

Density independent factors

Answer 9

factors that have effect on whole population regardless of its size
earthquakes, fires, volcanic eruptions, storms

Question 10

what do density independent factors cause

Answer 10

remove whole populations of species from a region
dramatically change population size

Question 11

interspecific competition definition

Answer 11

competition between different species

Question 12

intraspecific competition definition

Answer 12

competition between members of the same species

Question 13

when does interspecific competition occur

Answer 13

when 2 or more different species of organism compete for the same resource

Question 14

what does interspecific competition cause

Answer 14

reduction in resources available to both populations
due to less food organisms will have less energy for growth and reproduction so results in smaller populations

Question 15

what does interspecific competition cause if one is better adapted

Answer 15

less well adapted species will be outcompeted and if conditions remain the same less well adapted species will decline in numbers until it no longer exists in that habitat

Question 16

competitive exclusion principle

Answer 16

2 species competing for limited resources, the one that uses resources more effectively will eliminate the other

Question 17

Red and Grey squirrels

Answer 17

undergo interspecific competition in uk for food and territory
grey squirrel was native to north America but introduced to uk so quickly increased in numbers and resulted in decrease in red squirrel as grey can eat wider range of food and larger so can store more fat
increases change of survival and ability to reproduce so increases its population
this causes decrease in resources for red squirrel reducing ability to survive and reproduce

Question 18

stage 1 of intraspecific competition

Answer 18

when resource is plentiful in habitat all organisms have enough of the resource to survive and reproduce
- increase in population size

Question 19

stage 2 of intraspecific competition

Answer 19

due to increase in population size, many more individuals to share food and space available
resources now limited - not enough for all organisms to survive
- decrease in population size

Question 20

stage 3 of intraspecific competition

Answer 20

less competition as smaller population
less organisms competing for same resource
more organisms survive and reproduce
- increase in population size

Question 21

predation

Answer 21

an organism kills and eats another organism

Question 22

stage 1 of predator prey relationships

Answer 22

increase in prey population provides more food for predators = more can survive and reproduce= increase in predator population

Question 23

stage 2 of predator prey relationships

Answer 23

increase in predator population= eat more prey= decline in prey population
death rate of prey > birth rate of prey

Question 24

stage 3 of predator prey relationships

Answer 24

reduced prey population can’t support large predator population
intraspecific competition for food increases = decrease in size of predator population

Question 25

stage 4 of predator prey relationships

Answer 25

reduced predator numbers results in less prey being killed = more prey survive and reproduce = prey population increases

Question 26

Conservation

Answer 26

maintenance of biodiversity through human action and management
- dynamic
needs to adapt to constant change

Question 27

sustainable development in conservation

Answer 27

management of ecosystems so natural resources in them can be used without running out

Question 28

reclamation

Answer 28

process of restoring ecosystems that have been damaged or destroyed

Question 29

what techniques does reclamation involve

Answer 29

controlled burning of areas of rainforest to halt succession and increase biodiversity

Question 30

preservation

Answer 30

protection of an area by restricting or banning human interference so ecosystem is kept in its original state

Question 31

when is preservation commonly used

Answer 31

when preserving ecologically, archaeologically or paleontologically sensitive resources that can be easily damaged or destroyed by disturbances

Question 32

economic importance of conservation

Answer 32

provide resources that humans need to survive and to provide income
e.g rainforest species provide medicinal drugs, clothes and food that can be traded
other are used for timber and paper production

Question 33

social importance of conservation

Answer 33

many people enjoy natural beauty of wild ecosystems as well as using them mor beneficial health activities
e. walking, cycling, climbing

Question 34

ethical importance of conservation

Answer 34

all organisms have right to exist and most play important role within ecosystem
many people believe we shouldn’t have right to decide which organisms can survive and which we can live without
- have moral responsibility for future generations to conserve wide variety of existing ecosystems

Question 35

aims of sustainability

Answer 35

preserve environment
ensure resources are available for future generations
allow humans in all societies to live comfortably
enable less economically developed countries to develop through exploiting their natural resources
create more even balance in consumption of these resources between more economically developed countries and less economically developed countries

Question 36

small-scale timber production

Answer 36

use of coppicing
- tree trunk is cut close to the ground and new shoots from from the cut surface and mature
- eventually these shoots are cut and more are produced
- shoots are used for things like fencing

Question 37

how does rotational coppicing maintain biodiversity

Answer 37

trees never grow tall enough to block out the light

Question 38

what is rotational coppicing

Answer 38

woodland divided into sections
trees are only cut in particular section until all have been coppiced
coppicing then begins in another area to allow new coppiced trees to grow
continues until reach 1st coppiced trees which will have grown into mature sized trees

Question 39

pollarding

Answer 39

similar to coppicing but trunk is cut higher up to prevent deer and animals eating new shoots as they appear

Question 40

to ensure large scale timber production is sustainable what do the companies do

Answer 40

• selective cutting- only cut largest trees
• replace trees through replanting to ensure biodiversity and mineral and water cycles remain
• plant trees an optimal distance apart to reduce competition = higher yield as more wood produced per tree
• manage pests and pathogens to maximise yield
• ensure areas of forest remain for indigenous people

Question 41

major disadvantage of large scale timber production

Answer 41

habitats are destroyed, soil minerals are reduced and bare soil left is susceptible to erosion and trees bind soil together and remove water and maintain nutrient levels

Question 42

what technique is used for large scale timber production

Answer 42

felling
felled trees are destroyed and don’t grow back

Question 43

sustainable fishing techniques

Answer 43

• limit numbers on certain species of fish that are allowed to be caught in a certain area - allows fish to reproduce sufficiently to allow them to maintain population
• use of larger nets to allow immature fish to escape so only mature are caught allowing reproduction to continue
• only allow commercial and recreational fishing to happen at certain times of the year - protects breeding season of some fish to allow them to increase numbers
• introduction of fish farming to maintain supply of protein food whilst preventing loss of wild species